The comparative activity of norfloxacin with other antimicrobial agents against Gram-positive and Gram-negative bacteria
Abstract:
Norfloxacin (MK0366) displayed appreciable activity against the great majority of Gram-negative and Gram-positive bacteria. The minimum inhibitory concentration for 90% of isolates (MIC90) of the Enterobacteriaceae was 0.5 mg/l or less while for Campylobacter, Neisseria, Haemophilus MIC90s were 0.25 mg/l or less. Norfloxacin was also among the most active drugs tested against methicillin susceptible and resistant Staphylococcus aureus, Staph. epidermidis, enterococci and Pseudomonas aeruginosa with MIC90s between 0.5 and 4 mg/l.
Related Concept Videos
Antibiotic Selection
Overview
Combined Effects of Drugs: Synergism
Synergism is a useful mechanism where combining two or more drugs is more effective than each constituent used alone. Such combinations are also called supra-additive interactions. The drugs collectively enhance the final therapeutic effect by acting on different targets. Another advantage is that the low dose of each constituent drug is sufficient to achieve the desired effect. This helps reduce the duration of therapy and lower the adverse effects of these drugs.
Such synergistic combinations...
Such synergistic combinations...
Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence
Generic intravenous (IV) drugs are considered bioequivalent to their branded counterparts due to their 100% bioavailability upon administration. However, variations in stability among different drug products can significantly influence their therapeutic performance, even if they are pharmaceutically equivalent.Cefuroxime, a prophylactic antimicrobial, is often used as a single-dose IV injection for patients undergoing coronary artery bypass grafting surgery. A 3 g dose typically provides...
Antimicrobial Effectiveness
The effectiveness of antimicrobial agents depends on various factors influencing their ability to eliminate microbial populations. Larger microbial populations require more time for complete eradication, emphasizing the importance of population size analysis when evaluating antimicrobial efficacy.Microbial resistance to antimicrobial agents varies significantly. Highly resilient microorganisms include endospores, gram-negative bacteria, and non-enveloped viruses, while prions are exceptionally...
Inhibitors of Bacterial DNA Synthesis
Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...


